The present invention relates to the field of conveyors, and more particularly, to a modular pan assembly for an armored face conveyor, such as for handling coal in a longwall face mining system.
Armored face conveyors are the foundation for longwall face mining machines. Typically, the conveyor line pan module includes a hardened steel deck plate secured to supporting cast steel side rails. A plurality of these modular pans are assembled in end-to-end relationship to form a complete conveyor system for moving coal or other mineral along and away from the mine face under active excavation.
The pan assembly side rails additionally support the haulage system for the shearer which is the mine face cutting mechanism. A scraper chain extends along the entire conveyor system length with spaced flights serving to move the coal along the deck plate. Clearly, the strength of the armored face mining conveyor and its structural integrity is of a primary concern. Eliminating structural failures in the conveyor system, and thus minimizing down time, is important to assure an efficient longwall mining operation.
The operating environment of a mine is extremely harsh on mechanical equipment of all forms. The very nature of the work objective is to cut and remove abrasive material. Moreover, the abrasive material is fluidized in the presence of water and contaminated oil. In the case of material removal conveyors, the abrasive aggregate is wiped along the conveyor pan surfaces to exacerbate the grinding destruction.
In addition to the abrasive and corrosive nature of the environment, the machinery is subjected to extreme ranges of shock, mechanical twisting, racking and concentrated stresses due to uneven support surfaces.
Accordingly, mining equipment of all types and armored, longwall mine face conveyors in particular, suffer frequent disabilities and breakdowns.
In a successful earlier prior art effort to improve the operational life and reliability of longwall mine face conveyors, U.S. Pat. No. 5,131,724 taught a conveyor module construction method and apparatus wherein no conveyor module assembly welds were applied along the material transfer surfaces of the conveyor pan thereby avoiding exposure of the softer weld metal to the abrasive grinding of the mined and frequently, wet, aggregate as it slides along conveyor pan surface.
In this context, it is helpful to understand that the side rails are cast from abrasion resistant, high alloy cast steel. The decks are formed from hot rolled, abrasion resistive high alloy steel. Both materials are subject to stress cracking and hydrogen embrittlement. Collectively, both the rail and deck plate are not only considerably harder than the weld metals that hold the plate and rails together but application of a weld bead to these high alloy materials is more difficult than to more common metals.
Central to U.S. Pat. No. 5,131,724 invention was a key and slot relationship between the conveyor pan deck plate and the side rails. The side rails were cast with elongated slots in the rail web section between the top and bottom sigma flanges. Cooperatively, the deck plate longitudinal edges were notched to provide tabular key salients that were dimensioned to correspond with the slots.
In assembly, the deck keys were inserted through the side rail slots and secured by welding along the outside surfaces of the rail web and deck plate key edges. Material bearing loads were supported by the sectional shear profiles of the deck plate keys. The key plan surfaces were bedded within respective rail slots. The welds only had to resist the shear of lateral disassembly stress.
Although operationally successful and less expensive to manufacture than prior art predecessors, the U.S. Pat. No. 5,131,724 invention left some room for manufacturing cost improvement. It is, therefore, an object of the present invention to provide a longwall mine face conveyor having no welds in direct surface exposure to the mined aggregate and a minimum of assembly weld bead.
Another object of the present invention is provision of a shear resisting area corresponding to the deck plate thickness that extends continuously along the full length of the deck plate.
A still further object of the present invention is a meshing self alignment of matching surfaces between the longwall mine face conveyor deck plate and side rails to facilitate rapid and accurate assembly alignment.
An additional object of the present invention is a longwall mine face conveyor module that assembles with a minimum of welding bead.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. Even more objectives and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.